IRONSMITHINTEL
MEDIUMCVSS6.1
|
Actively Exploited
|CISA KEV|CVE-2020-35730|Auth: none — unauthenticated|Reboot: required|Manual only

Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability

Roundcube Webmail contains a cross-site scripting (XSS) vulnerability that allows an attacker to send a plain text e-mail message with Javascript in a link reference element that is mishandled by linkref_addinindex in rcube_string_replacer.php.

Published Dec 28, 2020 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure, partial data tampering. Federal agencies are required to remediate by 2023-07-13 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Cross-Site Scripting (XSS) (CWE-79) vulnerability in Roundcube Roundcube Webmail. An XSS issue was discovered in Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The attacker can send a plain text e-mail message, with JavaScript in a link reference element that is mishandled by linkref_addindex in rcube_string_replacer.php. Exploitation requires remote network access, low attack complexity, no authentication required, and user interaction required.

📧

Phishing link

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running webmail: v < 1.2.13, 1.3.0 ≤ v < 1.3.16, 1.4 ≤ v < 1.4.10; fedora: 32, 33; debian linux: 9.0
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2023-06-22 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2023-07-13.

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://roundcube.net/news/2020/12/27/security-updates-1.4.10-1.3.16-and-1.2.13
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2020-35730
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-35730
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